Posted on Categories Programming, TutorialsTags , , 1 Comment on An R function return and assignment puzzle

An R function return and assignment puzzle

Here is an R programming puzzle. What does the following code snippet actually do? And ever harder: what does it mean? (See here for some material on the difference between what code does and what code means.)

f <- function() { x <- 5 }

In R version 3.2.3 (2015-12-10) -- "Wooden Christmas-Tree" the code appears to call the function f() and return nothing (nothing is printed). When teaching I often state that you should explicitly use a non-assignment expression as your return value. You should write code such as the following:

f <- function() { x <- 5; x }
## [1] 5

(We are showing an R output as being prefixed with ##.)

But take a look at the this:

f <- function() { x <- 5 }
## [1] 5

It prints! Read further for what is really going on.

NewImage Continue reading An R function return and assignment puzzle

Posted on Categories Coding, Statistics, TutorialsTags , 16 Comments on Efficient accumulation in R

Efficient accumulation in R

R has a number of very good packages for manipulating and aggregating data (dplyr, sqldf, ScaleR, data.table, and more), but when it comes to accumulating results the beginning R user is often at sea. The R execution model is a bit exotic so many R users are very uncertain which methods of accumulating results are efficient and which are inefficient.

Accumulating wheat (Photo: Cyron Ray Macey, some rights reserved)

In this latest “R as it is” (again in collaboration with our friends at Revolution Analytics) we will quickly become expert at efficiently accumulating results in R. Continue reading Efficient accumulation in R

Posted on Categories Opinion, ProgrammingTags , , 4 Comments on R in a 64 bit world

R in a 64 bit world

32 bit data structures (pointers, integer representations, single precision floating point) have been past their “best before date” for quite some time. R itself moved to a 64 bit memory model some time ago, but still has only 32 bit integers. This is going to get more and more awkward going forward. What is R doing to work around this limitation?

IMG 1691

We discuss this in this article, the first of a new series of articles discussing aspects of “R as it is” that we are publishing with cooperation from Revolution Analytics. Continue reading R in a 64 bit world